The proposed research will investigate, in schizophrenics, nonschizophrenic psychotics and normals, the interrelationships between peripheral electrophysiological measures, brain electrophysiology, the activity of the catecholamine related enzymes monoamine oxidase (MAO) and dopamine beta-hydroxylase (DBH) and the psychological parameters of performance in auditory vigilance, two-flash-fusion threshold and iconic image formation tasks. This investigation will attempt to explain the differential sustained attention performance previously found in schizophrenic subjects on the basis of differential activity of catecholamines. The route whereby catecholamine alteration is hypothesized to have these effects is twofold: first electrophysiologically, through alterations to the early and later components of the evoked potential and differential cortical activation as indexed by power spectral analyzed EEG; secondly by alteration of the ability to form the iconic image in the early stages of information processing. Electrodermal subclassification of schizophrenics and controls, from skin conductance orienting response (SCOR) habituation, is hypothesized to be predictive of differential performance on the experimental variables referred to above.